Various types of chemical binders are used in basic unburned bricks and various types of basic castable refractories. Namely, well-known chemical binders such as organic binders such as tar, pitch, and phenol resins, and magnesium sulfate, alkali phosphates, alkali earth metal phosphates, alkali silicates, alkali borates, alumina cement, and the like are used. These chemical binders play a very important roll, increasing the binding power of the refractory, making the refractory easy to apply, and the like.
However, there are various problems with refractories employing the above-described chemical binders. Namely, when refractories employing organic chemical binders such as phenol resins, tar, pitch, and the like are used in an oxidizing atmosphere, combustion of carbon takes place, the texture deteriorates, and there is the drawback that adequate durability can not be obtained. Furthermore, with refractories using magnesium sulfate, various types of phosphates, and alkali borates, there is the fear of molten steel being contaminated by the phosphorus, sulfur, boron, and the like contained in the chemical binder. In addition, the hot strength of a basic refractory employing alumina cement or alkali silicate is low, the damage from wear by molten steel and the like is large, and the fire resistance is inadequate.